One-dimensional dynamics in locally heated liquid layers

Recent results on one-dimensional patterns in locally heated experiments are presented. A fluid layer is heated locally by a nearly one-dimensional heater, and subjected to both horizontal and vertical temperature gradients. Depending on the fluid depth and on the temperature difference established across the layer different convective regimes appear. When a very small temperature gradient is applied a basic convective state appears. It consists of two big rolls parallel to the heater and filling the convective cell. A primary instability in the homogeneous basic flow gives rise to a one-dimensional cellular stationary pattern. For higher values of the control parameters, time-dependent patterns appear through a secondary instability. Various regimes are analyzed: oscillations, traveling waves and alternating patterns. The hydrodynamic characteristics of these patterns are provided. Local temperature measurements allows to describe the physical mechanisms responsible for the instabilities. The similarities and discrepancies of the experimental data with some theoretical models are provided.